This invention relates to apparatus and method for making convolutely wound logs and, more particularly to logs such as toilet tissue and toweling.
Up to about 1950, stop-start winders (sometimes referred to as "rewinders") were used to convert jumbo-sized rolls of paper from the paper machine to retail-sized rolls. The critical feature in winding is cutoff and transfer. When the small roll or log is wound to its predetermined "count", it was necessary to sever the web transversely and transfer the web leading edge to a glue-equipped core. After about 1950, this was done automatically so that the winders could operate at continuous speed.
Two types of winders have been used. The most widely-employed for years has been the "center" wound type. These used a mandrel on which the core was ensleeved--with the mandrel being turned with a decreasing speed as the log increased in diameter. The cutoff and transfer problem was handled advantageously first by co-owned U.S. Pat. No. 2,769,600 and thereafter, when higher speeds were required, by co-owned U.S. Pat. No. 3,179,348.
More recently, surface winders have become popular because of being able to avoid the mechanisms used for the decreasing speed characteristic--thus being less complex and cheaper. These have employed a three-roll cradle, a stationary winding roll, a second winding roll which could be movable, and a movable rider roll.
The cutoff and transfer problem was addressed advantageously first by co-owned U.S. Pat. No. 4,723,724 and, more recently, by co-owned U.S. Pat. No. 4,828,195.
In the '195 patent, the web was severed, i.e., "cutoff" by being tensioned between a downstream point provided by the contact of the almost-finished log with the stationary winding roll and an upstream point where the core pinched the web against a breaker bar. Thereafter, the core had to rotate to bring a glue-stripe into engagement with the web. The rotation was necessary because the glue stripe on the core had to be between the winding roll and the web on the pinch plate. This resulted in excess material, i.e., slack, in the web leading edge and it also meant that the reversed leading edge was not under control.
According to the invention, the core is introduced into the nip between the stationary winding roll and the pinch bar without any contact with the web. The coaction of the stationary winding roll and the pinch bar causes the core to rotate to bring the glue stripe into confronting relation with the web when the core first contacts the web to provide the upstream pinch point. This results in severance and transfer substantially simultaneously so as to reduce both undesirable slack generation and an uncontrolled leading edge.